Telegraph breaking system



March 30, 1943. F. H. HANLEY TLEGRAPH BREAKING SYSTEM Filed Deo. 24, 1941 SSNW INVENTOR y v BY Mh.. ATTORNEY Patented Mar. 30, 1943 tiene TELEGRAPH BREAKING SYSTEM Frank Harold Hanley, Butler, N. J., assigner to American Telephone and Telegraph Company, a corporation of New York `Application December 24, 1941,' Serial No. 424,221

(c1. ir-.2)

5 Claims.

This invention relates to telegraph and teletypewriter systems and, more particularly, to

kapparatus for breaking the transmission over telegraph and teletypewriter systems.

In teletypewriter systems providing service for a plurality of subscribers stations over interconnected circuits, it happens that two or more of the interconnected subscribers stations may start to send at approximately the same time. Such a condition occurs frequently with systems bearing a heavy traffic. In such priorfsystems a considerable number of characters may be sent before it becomes apparent at one or several of the stations that another of the stations is sending. This is a troublesome condition which sometimes entails the loss of one or more messages. The situation has been found to be quite acute in systems having a type of message traic consisting especially of very short messages in considerable volume.

One of the objects of this invention is to provide a teletypewriter system which produces an instantaneous positive break as soon as aspacing signal is received in the loop and thereby reduce the difficulties experienced heretofore when two `or more stations attempt to send at the same time.

According to the present invention it is proposed to provide at a subscribers teletypewriter station an arrangement including, for example, a gas tube and a relay in addition to the usual sending and receiving equipment. This will be so set up that if a break or spacing signal is received at a subscribers station, the gas tube will become ionized and the relay will become operated to break the stations transmission.

This invention will be better understood from the more detailed description hereinafter following when read in connection with the accompanying drawing showing one embodiment of the invention merely for the purpose of illustration.

Referring to the drawing, there is shown a subscribers teletypewriter station designated W which may include the usual teletypewriter equipment such as the sending contact apparatus TTY, the break Contact Ko, the line relay LR, the receiving magnet RM which is controlled by the line relay LR, and the transmitter-distributor TD which controls the sending contact apparatus TTY. This teletypewriter equipment is connected to a loop including conductors L1 and L2 which may extend to a central oiice as shown. Bridged across the sending contact equipment TTY and the contact Ko is a. circuit including two approximately equal resistors Z1 and Z2 which are arranged in series relationship. The control gap Di--Dz of-a gas-filled tube T is connected between the point Co which is the terminal common to resistors Z1 and Z2 and ground. The plate or anode P of tube lT is connected in series with the winding of a relay Ro, the key K1, battery Bo and ground. When the enclosed gas becomes ionized due to the presence of a sufficient or predetermined voltage on the controlgap Di-Dz, current 'will flow from battery Bo through the winding of relay Ro to operate relay Ro, as will be explained hereinafter.

- The armature of relay Ro will then open the circuit of the transmitter-distributor TD and the station W will be unable to send teletypevvriter characters or signals to the central office.

At the central ofce two jacks J1 and .lzare shown connected to the loop conductors Li and L2, respectively, jack J1 being associated with a line L3 which may extend to a teletypewriter subscriber X, jack J2 being associated with a line L4 which may extend to another teletypewriter subscriber Y. It Will be understood that lines L3 and L4 may pass through repeater circuits `o1 well-known type (at other central oiiices) and that these lines may also lead to still other subscribers stations (not shown). y

The jack J1 is connected through the upper or Vmain winding of a sending relay SR1 to the armatureof a receiving relay RR1. The armature of the sending 'relay SR1 is connected through the upper or main windingof the receiving relay RR1 to line La. VLikewise jack J2 is connected to the armature of a corresponding receiving relay RR2 through the lower or main winding of a corresponding sending relay SR2. Moreover, the armature of relay SRzis connected through the upper or main winding of relay RR2 to line L4. Each of the sending relays SR1 and SR2 and each of the receiving relays RRi and RR2 may have a second or biasing winding as shown in the drawing.

The apparatus is shown in its idle condition in the drawing. When the subscriber at-station W Wishes to send, he will operate the transmitter-distributor TD whichwill then operate the sending contact equipment TTY in a well-known manner. The marking and spacing* pulses of each teletypewriter character will be transmitted rover line L1 of the loop to the central oilice. There the received pulses will operate relay SR1 in the usual way to alternately connect oppositely poled batteries B1 and B2 through the main Winding of relay RR1 to lineV L3 which extends to station-X. The pulses emanating from the sending equipment TTY will likewise pass through the upper or main winding of the line relay LR, over the loop conductor L2 to the central office, the received pulses operating relay SR2 in a Well-known manner. The armature of the latter relay will connect oppositely poled batteries B3 and B4 through the main winding of relay RRz to line L4 which extends to station Y. At station W the relay LR will repeat the pulses to the teletypewriter receiving magnet RM to provide the home copy.

Likewise signals may be transmitted from one of the other stations, such as X, to stations W and Y. As the marking and spacing pulses travel over line L3, they cause the receiving relay RRi to operate to connect the oppositely poled batteries B5 and Bs through the main Winding of relay SR1 to the loop conductor L1. These pulses operate the relay LR and are thereby repeated to the receiving magnet RM at station W. These pulses return over loop conductor L2 and accordingly operate the relay SR2 to connect batteries B3 and B4 to the line L4. The pulses are thus received at station Y. Signals may be transmitted from station Y over line L4 to stations W and X, but this need not be described.

In the idle condition of the apparatus the oppositely poled batteries B5 and B7 are connected through the armatures and marking contacts M of relays RR1 and RR2 and over loop conductors L1 and L2, respectively, to the series resistors Z1 and Z2. These resistors therefore carry no current during the idle condition because these l resistors are short-circuited by the contacts oi the transmitter TTY. Asl the point Co is at the approximate electrical center of the loop circuit, practically no voltage will be applied to the control gap D1--Dz of tube T and therefore the gas within tube T will remain deionized. The gas within tube T will likewise remain deionized when signals are sent from station W over loop conductors Li-Lz to the central oihce. This is because such signals will not move the armatures of relays RR1 and RRz from their marking contacts M. When the armatures of relays RR1 and RRz are on their contacts M, oppositely poled batteries B5 and B7 of equal potential will be connected to the loop conductors Li-Lz under such conditions and point C0 still being at the approximate electrical center of the circuit, practically no voltage will be applied to the control gapl of tube T. The opening and closing of the contacts of the transmitting equipment TTY will therefore fail to cause tube T to flash. While signals are being transmitted from station W, a small current will flow through resistors Z1 and Z2.

However, if one of the stations, such as station X, starts to send, whether station W is sending or not, the armature of relay RRi will thereupon move to its spacing contact S. In that event the batteries Bs and BPI-which are of the same polaritywill be connected by loop conductors L1-L2 Vto resistors Z1 and Z2 and the potential of electrode D1 of tube T will be raised to a positive potential equal to that of batteries B6 and B7 while the other control gap electrode Dz remains grounded. Hence the gas within the tube will become ionized. Current will then flow from battery Bo through the winding of relay Rn and over the main gap P-D2 of tube T1 thereby operating relay Ro. The operation of relay Ro will open the circuit of the back contact of its armature and hence the transmitter-distributor tape stop magnet TD will receive no more `current from battery B0. Therefore the teletypewrlter sending equipment TTY will cease to operate. The ionization of the gas within tube T, the consequent operation of relay Ro and release of the transmitter-distributor TD in response to a break or spacing pulse from one of the stations such as X or Y, represent important features of this arrangement.

When a break or spacing pulse arrives over line L4, batteries B5 and B8 will both be connected to the loop circuit L1-L2. The potential of electrode D1 will then be negative suiciently to ionize the tube T as already considered heretofore. The operation is in other respects similar to that already described.

The potential of battery B0 is higher than that required to sustain ionization of the gas within tube T after ionization has previously been initiated by the application of a predetermined voltage to the control gap D1-D2. Hence relay Ro will remain operated and the teletypewriter at station W will remain unoperable until the battery B0 is disconnected from the transmitter-distributor circuit. This may be accomplished by operating the non-locking key K1 to restore the circuit to its initial condition, whereupon relay Ru will be released and tube T dionized. The transmitter-distributor TD will be reconnected to battery Bo through the armature and back contact of relay Rn, thereby enabling the local teletypewriter apparatus to operate thereafter. The tube T will, however, remain dionized until another break or spacing pulse arrives from one of the stations X or Y.

Thus it will be apparent that when one of the stations X or Y is sending, the station W will be unable to send although all signals will be received by the relay LR at station W and repeated to the receiving magnet RM.

If at any time station W and station X, for example, both attempt to send, and station X sends its rst spacing pulse however short before the spacing pulse from station Y arrives, the armature of relay RR1 will move to its spacing contact, tube T will iiash and render impossible any transmission from station W. Thus station X will obtain control of the circuit and disable station W so that the latter station Amay not send any signals. The disability of the station W transmitter will be indicated by the illumination of tube T which is an unpainted gas tube of, for example, the 313C type.

It will be understood that an arrangement including an unpainted gas tube such as T and a relay such as R0 may be installed at stations X and Y and at any other points. Each such arrangement will respond to a break signal to stop the local transmitter and prevent the loss of any part of the message to be transmitted.

While this invention has been shown and described in a certain particular embodiment merely for the purpose of illustration, it will be understood that the general principles of this invention may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

What is claimed is:

l. In a telegraph system, the combination oi a loop circuit over which signals may be transmitted, a transmitter connected to said loop circuit, a pair of equal resistors connected in series with each other across said transmitter, a gas tube connected to the terminal common to said resistors, means responsive to a break signal received over said loop circuit to ionize the gas within said tube, and means responsive to the ionization 0I the gas Within said gas tube to prevent any furtner transmission of signals by said transmitter over said loop circuit.

2. In a telegraph system, the combination of a telegraph transmitter, a pair of equal resistors connected in series with each other across the terminals of said transmitter, a gas tube connected between the terminal common to said resistors and ground, means responsive to a break signal to fire said gas tube, and means responsive to the ring of said gas tube to prevent said transmitter from transmitting signals.

3. A breaking arrangement for the transmitter oi a telegraph system, comprising a gas tube having a control gap and a main gap, a relay connected to the main gap of said tube, the control gap of said tube being connected to the terminals of said transmitter, control apparatus for said transmitter, means responsive to a break signal to fire the control gap of said tube, and means responsive to the operation of said relay Ato operate said control apparatus to prevent transmission by said transmitter.

4. In a teletypewriter system, the combination of a teletypewriter, a loop connected to said teletypewriter, a control device to stop said teletypewriter, and means responsive to a break signal received over said loop to operate said control device so as to stop said teletypewriter, said means including a gas tube, means for applying voltages received over said loop to said gas tube to ionize the gas contained therein, and means responsive to the ionization of the gas within said tube to open the circuit of said control device.

5. In a teletypewriter system, the combination of a teletypewriter, a loop connected to the contacts of said teletypewriter, a control device for said teletypewriter, a relay the armature of Which is connected to said control device to control the flow of current through said control device, a resistor connected to the contacts of said teletypewriter, and a gas tube having its control gap connected between a point on said resistor and ground, the main gap of said tube being c0nnected in series with the winding of said relay.

FRANK HAROLD HANLEY. 

